Helicopter-hoist equipment today typically includes a lifting device such as a hoist, which is attached to the helicopter, a hoist cable, and a hook located at the distal end of the cable for direct or indirect attachment to a person, animal, or object for rescue. The hoist usually has a rotary drum for winding in and out the cable that serves to lift or transport the load. A crew member in the helicopter usually controls the raising and lowering of the hook.
Various types of hoist-rescue systems for helicopters have been developed since the 1950s. While most hoist-rescue systems are electro-mechanical in nature they generally lack positional sensors and information intelligence. This creates challenges for the pilot of the helicopter and rescue crew. For instance, when the hook end of a cable is lowered from a helicopter in bad weather, at night, in dust or smoke, and in combat missions, it is often difficult to see the hook in relation to the person or object being rescued. There is also no way for the flight crews (i.e., pilot, copilot, hoist operator, crew chief, and other observers) to all understand the complete situation of the rescue, victims, and helicopter.
Other considerations include a lack of real-time information to the rescue crew about the weight and stresses being exerted on the hoist-rescue system during a rescue, and the position of the hook relative to the ground. This can create unsafe conditions for both the rescue crew, and target during a rescue mission.
And because there is little information about the physical loads and stresses placed on the hoist-rescue system during a mission, personnel responsible for maintaining the rescue equipment often have little direct insight into the condition of the equipment as a result of any given rescue mission. Consequently, maintenance personnel must periodically perform time consuming and costly inspections of the rescue equipment to check for possible damage. Further, maintenance of rescue equipment is typically performed at periodic intervals rather than tied to a particular rescue mission in which the equipment may have been overstressed or damaged.
Also flight crews are often unable to fully and reliably debrief and review the events of a flight mission, because they are forced to work off memory after the flight mission and because they lack quantitative information related to the rescue operation that would be valuable to maintenance personnel.